Water-based primers

Water-borne primers may or may not contain chromate-based corrosion inhibitors. The limited solubility of chromate salts in water makes them less than ideal for use in water-based primers, and much work has gone into developing alternatives [36], but the performance of recently developed water based primers using strontium chromate as the corrosion inhibitor is excellent, however, and appears equivalent to the solvent-borne analogues [37]. 

Hot melts are sometimes applied on top of a water-based primer, as mentioned above. The primer penetrates the paper and stiffens the ends of the paper sheets prior to their being attaehed to the eover with a hot melt overlayer. In some eases a pre-primer is employed whieh aetually penetrates eaeh sheet and stiffens the eore of the paper as well. 

Volatile organics in the coating film are deemed unacceptable from the environmental point of view and are giving way to water-based inhibitive primers. Some examples of water-based primers are of the acrylic latex type, as well as epoxies and water-borne... 

Chem. Descrip. Water-reducible epoxy ester in 2-butoxy ethanol Uses Epoxy for coatings, MIL-P-5 32 primers, topcoats for metal consumer goo, maintenance and dip coatings modifier for latex coatings to improve corrosion resist. can be formulated into VOC-compliant water-based primers/enamels... 

Chem. Descrip. Basic zinc molybdenum phosphate hydrate Chem. Analysis 55% Zn, 38.5% PO4,1.7% M0O3 Uses Corrosion inhibitor, pigment for water-based primers (e.g., styrene-acrylic dispersions)... 

Research is now strongly centred on prodncing primers with low volatile organic contents, by using water as the primary solvent or dispersion medium or actual water-based primers where the organic solvent content is zero. For similar reasons of Environment and the impact of adhesive technology, a move to non-chromate systems is also under way. 

This is particuiariy necessary with water-based primers and bonding agents. Soivent borne bonding agents wet out a ciean metai surface with far greater ease than do the water-based products. 

Water-Based Primer/Adhesive for Extrusions end Laminations to Clay Coated Paper Surfaces... 

Water-based Primer/Adhesive for Polypropylene and Other Fllais... 

Polaqua 138 is a water-based primer specifically developed for water resistant bonds of polyethylene to aluminum foil by lamination or extrusion. It is applied by convmtitHial application methods (gravure, flexo, rod, roll, etc.) to the accepting substrate. The primer must be thoroughly and absolutely dry before introduction of the extrudate or lamination. Polaqua 138 should be applied as received using light application weights. 

Santel HR-97 is a water-based primer for all grades of films which is used to ioq>rove printing adhesion and lay down properties. Certain films are difficult to print and inks may not have adequate adhesion for packaging applications. J >plying Santel HR-97 to the surface of the film, prior to printing, will greatly improve ink lay down on press and final print adhesion values. 

Water-Based Primer/Adheslve for Extrusions and Laminations... 

For cleaning/priming operations there are also new developments. One trend is to apply the primer in a water-based form. In this invention, a water based primer was developed using water reducible polyurethanes. The primer is for general use but has been... 

If water-based primers are being manufactured, then the situation is slightly more involved. The use of water means that only glass-lined or. stainless steel vessels can be used for the final stage of mixing. In many instances, solid raw materials will not be... 

Lead silicate is used mainly in water-based primers for wood, where it reacts with tannates to prevent them from bleeding and discoloring succeeding paint coats. Lead silicate may be eliminated from home use because of restrictions on the use of lead. 

Primer vehicles based on emulsion polymer technology were introduced in the 1970s and have shown a steady increase in market share over the past 30 years. They are used in a variety of exterior and interior coating applications. Stain blocking primers are one of the most popular types, and are used to prevent discoloration of topcoats by a variety of materials, including tannin stains from wood, children s marker stains, water stains and nicotine stains. Water based primers generally block the transport of stains by two principle mechanisms ... 

While the stain may be visible at the surface of the primer coating after drying, it is effectively locked into the film and does not lead to discoloration of the topcoat. Binders for stain blocking primers are usually based on relatively hydrophobic emulsion polymers with acrylic or styrene acrylic compositions. Primers are expected to have excellent adhesion, and water based primers are formulated to adhere to a variety of substrates including metal, wood, and chalky or aged re-paint surfaces. Since this level of performance may not be needed, or achievable, in many topcoat formulations, the use of specialized primers offers a flexible and cost effective way to meet the performance needs of many different coating apphcations with a limited number of optimized topcoat products. 

---